Method and apparatus for stretching and crystallizing the neck finish of a molded plastic article

ABSTRACT

Apparatus and method for making a molded plastic article having a stretched and crystallized neck finish. In one embodiment, a series of platforms are carried by a conveying apparatus for transporting a series of molded plastic articles along a predetermined path of travel through one or more treatment stations. At a finish widening station, the molded article, having a relatively wide and thin-walled blow-molded body portion, and a relatively narrow and thick-walled unexpanded neck finish portion, is positioned to enable insertion of a mandrel into an open top aperture of the finish portion to widen the finish.

FIELD OF THE INVENTION

The present invention relates to molded plastic articles, such as foodand beverage containers, and to a method and apparatus for manufacturingsuch articles. In various embodiments, a method and apparatus aredisclosed for making a plastic container having a stretched andcrystallized neck finish.

BACKGROUND OF THE INVENTION

Molding processes (e.g., injection, compression, extrusion) are knownfor making preforms which are then expanded (e.g., blow molded) to formcontainers and other packaging articles. Typically suchpreforms/containers have a relatively narrow-neck finish, to which aclosure such as a screw-on cap can be attached. However, in manyapplications it would be desirable to provide a wide-neck container forease of access or pouring. It may also be desirable to heat-treat orotherwise process such a wide-neck finish of the container for variousapplications (e.g., high temperature filling or pasteurization) whilestill maintaining accurate dimensions of the neck finish, and inparticular any threads on the finish.

Molding processes and equipment for making bottles having various neck(a/k/a finish) sizes are disclosed in U.S. Pat. No. 6,884,382, U.S. Pat.No. 6,572,812, U.S. Patent Publication No. 2005/0003123 and U.S. PatentPublication No. 2005/0236356, the disclosures of all of the foregoing ofwhich are incorporated herein by reference in their entirety as if fullyset forth.

SUMMARY OF THE INVENTION

The present invention relates to the treatment of molded plasticarticles, such as preforms and containers.

In one embodiment of the invention, an apparatus and method are providedfor treating a series of molded plastic articles, each article having arelatively wide and thin-walled blow-molded body portion and arelatively narrow and thick-walled unexpanded neck finish portion. Aseries of platforms are carried by a conveying apparatus that transportsthe platforms along a predetermined path of travel through a finishwidening station. Each platform has a top surface for engaging a bottomsurface of the body portion of one article, and a mating mechanism forengaging a sidewall surface of the body portion of the one article. Thefinish widening station includes a mandrel insertable within andremovable from an open top aperture of the finish portion, to widen thefinish portion. The mating mechanism adjustably receives and engagesagainst the sidewall portion to hold the article in a steady positionrelative to the platform during insertion and removal of the mandrelfrom the aperture. One or both of the mandrel and article may be rotatedduring insertion and/or removal of the mandrel from the finish.

In another embodiment, the predetermined path of travel further includesa finish crystallizing station having a heating device that heats thewidened finish portion for a time and temperature selected tocrystallize at least a portion of the widened finish. A sizing device,insertable within and removable from the widened finish portion,supports the finish during the crystallizing step. The article is stillsupported on the platform so that the mating mechanism engages thesidewall portion in a steady position relative to the platform duringinsertion and removal of the sizing device from the widened finish. Oneor both of the sizing device and article may be rotated during insertionand/or removal of the sizing device from the finish.

In another embodiment, an apparatus is provided for treating a series ofmolded plastic articles. The apparatus includes a series of platformscarried by a conveying apparatus that transports the platforms along apredetermined path of travel through one or more treatment stations.Each platform, as previously described, has a top surface and a matingmechanism for engaging the body portion of one article. A depositmechanism deposits one article on each platform in an orientation thatdirects the bottom surface of the body portion into engagement with thetop surface of the platform and arranges the finish portion in anorientation that enables an operational mechanism of the treatmentstation to engage the finish portion. As previously described, themating mechanism adjustably receives and engages against the sidewallportion to hold the one article in a steady position on the platformduring transport of the article through the one or more treatmentstations.

One such treatment station may provide a mandrel that is forciblyinsertable within and removable from an open top aperture of the finishportion, to widen the finish portion. The one or another station mayinclude a heating device that heats the finish portion prior to theinsertion of the mandrel. The one or another treatment station mayinclude a cooling device that cools the widened finish portion. The oneor another treatment station may provide a heating device that heats thefinish portion for a time and to a temperature selected to crystallizeat least a portion of the widened finish portion. At the crystallizingstation a sizing cup may be positioned within the widened finish portionfor maintaining the finish size during the crystallizing treatment.

In another embodiment, a method is provided for treating a series ofmolded plastic articles through one or more treatment stations having anoperational mechanism. The method includes steps of providing a seriesof platforms that are transported by a conveying apparatus through theone or more treatment stations. Each platform has a mating mechanismhaving a recess that adjustably receives and engages a relatively wideand thin-walled blow-molded body portion of the article. Each article isdeposited on a platform and within the recess of the mating mechanism inan orientation that aligns a finish portion of the article in a positionthat enables operational engagement with an operational mechanism at thetreatment station. The articles are conveyed on the platforms throughthe one or more treatment stations, while treating the articles with therespective operational mechanism. The step of treating may comprisewidening the finish portion, for example by inserting an expansionmandrel within an open top aperture of the finish portion to widen thefinish portion. The step of treating may include heating the finishportion to enable insertion of the mandrel. The treating may furtherinclude cooling the widened finish portion. The cooling may be bothinterior conductive cooling and exterior convective cooling of thewidened finish portion. The step of treating may further compriseheating of the widened finish portion to crystallize at least a portionof the widened finish portion. Preferably, a sizing device is providedin the expanded finish portion as it is being heated and crystallized.

In one preferred embodiment, the step of treating includes heating andwidening the finish portion by inserting an expansion mandrel within anopen top aperture of the finish portion, cooling the widened finishportion by interior conductive cooling and exterior convective cooling,and heating and crystallizing at least a portion of the widened finishportion while a sizing device is positioned in the widened finishportion.

In one embodiment, the mandrel has a lower tapered body portioninsertable into the open top aperture of the finish portion for wideningthe neck finish portion from a first neck size to an expanded secondneck size. The lower body portion is heated. The mandrel furtherincludes an upper body portion of the second expanded neck size. Atleast a portion of upper body portion is cooled for cooling the expandedneck finish portion. The outer surface of the mandrel preferablycomprises a low friction material, which may be provided as an outerlayer. Preferably, the mandrel further includes an exterior coolingmechanism for directing a stream of cooling fluid (e.g., air) intocontact with an exterior surface of the expanded neck finish portion,the exterior cooling fluid being provided in the form of a halo or ring,around the expanded finish. The exterior cooling mechanism may include acollar mounted on the upper mandrel body.

In accordance with one method of expanding a neck finish portion of amolded article, the method includes the steps of providing a mandrel forwidening the neck finish from a first size to a second size, the mandrelhaving a heated lower tapered body portion which increases in crosssectional size along its length from a distal end to a proximal end, andhaving a cooled upper body portion positionable within the expanded neckfinish, forcibly inserting the lower mandrel portion into an open topaperture of the neck finish to widen the neck finish portion from thefirst neck size to the expanded second neck size, and cooling theexpanded neck finish while positioned on the upper body portion. Thestep of cooling may include convective cooling of the exterior of thewidened finish portion.

In accordance with another embodiment, a method is provided for forminga wide mouth container including the steps of molding a container havingan unexpanded neck finish portion of a first neck size, widening theneck finish to a second neck size, inserting a sizing device into thewidened finish for supporting the widened finish, heating the widenedfinish while positioned on the sizing device to a temperature and for atime selected to crystallize at least a portion of the widened finish,cooling the crystallized finish, and removing the sizing device from thefinish. One or both of the finish and sizing device may be rotatedaround an axis of insertion during insertion and/or removal of thesizing device from the finish. The step of cooling the crystallizedfinish prior to removal of the sizing device may be accomplished bydirecting cooling air into the sizing device to draw heat from thefinish (the sizing device serving as a heat sink). The finish mayinclude threads on an outside surface of the finish, and the step ofheating the widened finish may comprise heating the outside surface ofthe finish at a time and temperature selected to crystallize the finishincluding the threads along a selected depth of the finish from theoutside surface toward the inside surface.

In another embodiment, an apparatus is provided for crystallizing a neckfinish of a molded container, the apparatus including a sizing devicefor supporting an inside surface of the neck finish of the container, amechanism for inserting the sizing device into an open top aperture ofthe finish, a heating mechanism that directs heat onto the outsidesurface of the finish while the sizing device is inserted within thefinish, and the heating mechanism being controlled to heat the finish toa temperature and for a time sufficient to crystallize the finish alonga selected portion of the depth of the finish from an outside surfacetoward the inside surface of the finish. The sizing device may comprisea hollow cup shaped metal body having an outer layer of a low frictionpolymer material. A rotation device may allow rotation of one or both ofthe sizing device and the finish upon insertion and/or removal of thesizing device from the finish.

The terms “narrow-neck” finish and “wide-mouth” finish are employed in arelative sense in the present application. For example, in the plasticbeverage/food container industry a “wide neck” or “wide-mouth” finishgenerally has an outside diameter (E diameter) greater than 2.0 inchesor 50 mm, while a narrow-neck finish has an outside diameter equal to orless than 2.0 inches or 50 mm. As further examples, 28 mm and 43 mmfinishes are typical narrow-neck finishes in the plastic containerindustry, although the present invention is by no means limited to theseparticular finish diameters. A 63 mm finish is a typical wide-neckfinish in the plastic container industry, although the present inventionagain is not limited to wide-neck finishes of this particular size. An83 mm finish is another conventional wide-neck finish size.

These and other features and/or advantages of various embodiments of theinvention may be understood by referring to the following detaileddescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of one embodiment of a method andapparatus for finish expansion and crystallization according to theinvention;

FIG. 2 is a cross-sectional view of a preform positioned in a blow moldfor expanding the preform body to form an intermediate containerproduct;

FIG. 3 is a schematic elevational view of an intermediate containerproduct formed in the blow mold of FIG. 2;

FIG. 4 is a schematic elevational view of a container formed byexpanding and crystallizing the finish of the intermediate containerproduct of FIG. 3;

FIG. 5 is a schematic diagram of one embodiment of a method andapparatus for sequential positioning of a neck expansion mandrel in thefinish of each of a series of intermediate container articles to producea wide mouth finish in each article;

FIG. 6 is a side view of one embodiment for rotating a series ofindividual supporting structures (platforms) for carrying a series ofintermediate container articles to be conveyed through the finishwidening process;

FIG. 7 is a top schematic view of a platform having movable supportposts or fingers forming an adjustable recess for engaging the body of acontainer article;

FIG. 8 is a schematic diagram of one embodiment of a method andapparatus for sequential insertion and removal of a sizing device intoand from an expanded finish at a finish crystallizing station;

FIG. 9 is a side cross-sectional view of the sizing device of FIG. 8;

FIG. 10 is a detailed cross-sectional view of a neck expansion mandrelfor use in one embodiment of the invention; and

FIG. 11 is a series of detailed cross-sectional views of the mandrel ofFIG. 10 being used to expand a neck finish.

DETAILED DESCRIPTION

The figures show one embodiment of a process and apparatus for wideningthe neck of a molded article according to the invention. FIG. 1 is anoverview of the process and apparatus, while the later figures providemore detail of the individual steps/components.

In the embodiment shown, a narrow-neck preform 10 (see FIG. 2) is firstinjection molded (step 2 of FIG. 1) and then blow molded (step 4 ofFIG. 1) to form an intermediate container product 22 (see FIG. 3) havinga relatively wide and thin-walled expanded body portion 24 with the samerelatively narrow and thick-walled unexpanded neck finish 14. A seriesof such intermediate container products 22 are formed as a result ofblow mold step 4 and deposited (one each) onto a series of supportingstructures (platforms or pucks), shown generally in FIGS. 1 and 5 asdisc-like elements 60, for supporting and conveying the individualintermediate container products 22 upright and in a defined spaced apartrelation while carried by a conveyor 67 driven along a path 6. Themolded articles 22 are heated during the blow molding process and,before being deposited onto the platforms, are cooled to a temperatureat which they will not be deformed by the conveying apparatus.

In the embodiment of FIG. 1, the blow molded narrow-neck intermediatecontainer products 22 are routed through a first oven treatment station62 that heats at least the neck finish portion 14 (FIG. 3) of eacharticle 22 to a temperature sufficient to enable the finish 14 to bemechanically widened/expanded (at expansion station 26) by forcibledownward insertion of a mandrel 28, as described in detail below. Asshown in FIGS. 5 and 11A-D, an outer surface of the rotating taperedmandrel 28 engages an interior surface 52 of the finish and radiallyenlarges the narrow finish 14 to form a widened finish 36 (see FIG. 4).A lower tapered portion 50 of the mandrel 28 is heated by a flow of hotwater (HW) through fluid channels in the portion 50, to maintain thefinish at a desired expansion temperature (see FIG. 11B). After thefinish is fully expanded by the lower tapered portion 50, the widenedfinish 36 is positioned over an expanded upper cylindrical portion 35 ofthe mandrel. The upper mandrel includes a body portion 37 which iscooled by a flow of cold water (CW) through fluid channels in the body37 (see FIG. 11C). The interior surface 52 of the expanded neck 36 iscooled by conduction contact with the body 37. Also, while the mandrel28 is still inserted within the expanded neck 36, a jet of cold air (A)in the form of a ring or halo is applied via a mandrel collar mechanism70 to and around the outside surface 54 of the widened finish 36 toeffect convective cooling.

Upon removal of the neck-expanding mandrel 28 from the cooled widenedneck 36, a sizing device 100 (see FIG. 8) is preferably inserted withinthe widened neck 36. A series of expanded finish articles 40, each stillmounted on an individual platform 60 and with a sizing device 100inserted in the expanded finish 36, are routed by the conveyor 67through a second oven treatment station 63 such that at least someportion of the widened neck finish portion 36 of each article 40 isheated for a time and to a temperature sufficient to effect at leastpartial crystallization of the polymer material of the finish 36. Asshown in FIG. 1, after emerging from the second oven treatment 63, theenlarged crystallized finish is cooled. The sizing device is cooled andserves as a heat sink to draw heat out of the finish. The sizing device100 is then removed from the finish 36, and the finished bottles 40 withexpanded and crystallized finishes are then removed from the platforms.The conveyor 67 with empty platforms (pucks) is routed back along path 6a to the entry of the first oven treatment station 62 for receipt of newintermediate container products 22 on the platforms 60.

As shown in FIG. 2, a typical preform 10 has a tubular body 12 closed atthe lower end and an integrally molded finish 14. The finish 14 has oneor more external threads 16. The threads can be external male threads orinternal female threads (not shown) that are configured to be matablewith the threads of a complementary closure or cap (not shown). Thepreform 10 is typically fabricated in an injection, extrusion orcompression molding operation, and can be of monolayer or multilayerconstruction. Examples of molding processes are disclosed in, forexample, U.S. Pat. No. 4,781,954, the disclosure of which isincorporated by reference herein as if set forth in its entirety. Themolded preform 10 is then positioned in a blow mold 18 (FIG. 2) forexpansion of the preform body 12 within mold cavity 20. Application of astretch rod and air under pressure to the interior of preform 10 expandspreform body 12 to the confines of mold cavity 20. The resultingintermediate container article 22, as illustrated in FIG. 3, has arelatively wide and thin-walled blow-molded body portion 24 (formed byexpansion of preform body 12), and a relatively narrow and thick-walledneck finish portion 14 with external threads 16 (same as preform neck14).

As noted with reference to FIGS. 1 and 5, a series of intermediatecontainer articles 22 are deposited (one each) on a series of platforms(or pucks) 60 for routing initially to the first oven treatment station62, followed by the neck finish expansion station 26 (62 and 26 may alsobe collectively referred to as one heat treatment and neck expansiontreatment station). Typically when the mandrel or plug 28 is beinginserted into narrow-neck finish 14 of the intermediate article 22, themandrel 28 is being rotated (see arrow 30 in FIG. 5) about its insertionaxis. Alternatively, mandrel 28 can be held stationary, and the article22 rotated during insertion of mandrel 28 (see arrow 33 in FIG. 6), orboth the mandrel and article can be rotated. As shown in FIGS. 5 and10-11, mandrel 28 has a tapered or conically shaped lower portion 50,with a preselected minimum lower end diameter 32 that is less than theinside diameter of the narrow neck preform finish 14 (as initiallymolded), and mandrel 28 has an upper intermediate portion 34 having adiameter equal to or slightly greater than (to allow for relaxation) thedesired inside diameter of the final widened finish 36 of the bottle 40.Mandrel 28 also has a cylindrical upper portion 35 (having the samediameter as portion 34) to fit into the expanded container finish 36.The lower body 51 (including portions 50 and 34) of plug/mandrel 28 ispreferably heated, e.g., by injection of a flow of hot water (HW)through channels 86 provided within the lower body of the mandrel 28, soas to maintain the previously heated finish at a temperature whichfacilitates expansion. The expanded finish 36 is then subsequentlycooled via input of cold water (CW) flow via flow channels 84 providedwithin an upper body 37 (including portion 35) of the mandrel 28, byconduction contact of body 37 with interior finish surface 52. Theexterior surface 54 of the widened finish 36 is also preferably cooledvia application of a jetstream of air (or other cooling fluid) thatforms a halo or ring in chamber 74 formed around the exterior of thewidened finish 36 via collar 70 to assist in cooling of the expandedfinish. As a further alternative, the upper mandrel body 37 can beheated (before being cooled) by fluid flow through one or more channelsto facilitate the positioning of the expanded neck finish onto the body37; this would be followed by cooling the mandrel body portion 35(through the same or different fluid channels) in order to cool theexpanded neck finish.

The step of withdrawing 42 the mandrel 28, again preferably withrotation 31 (see FIG. 5), results in a container article 40 with anexpanded finish 36 (see FIG. 4). This expanded neck container 40 has abody 24 and an integral expanded finish 36 with expanded threads 38 andan expanded aperture diameter relative to the diameter of thenarrow-neck 14 of the initially blown article 22. Expanded finish 36 hasexternal threads 38 with substantially the same relative geometry as theoriginal injection molded preform threads 16, but which are radially andcircumferentially expanded along with the finish. Thus, threads 38 areexpanded or stretched as compared with preform threads 16, but otherwisehave a geometry determined by the geometry of threads 16 as molded,which are more sharply defined and detailed than threads that can beobtained by blow molding.

More specific and alternative embodiments of various apparatus andmethods for expanding and/or crystallizing a neck finish according tothe invention are described below.

The intermediate blow molded articles 22 can be automatically depositedby any of the known deposit mechanisms 5 (FIG. 1) for placing articles22, one each, onto platforms 60 as the platforms are moving on conveyor67 along path 6. The articles 22 are preferably deposited in anorientation such that a bottom surface 25 of each article 22 is guidedinto engagement with a top support surface 200 (FIG. 5) of a platform60. Once deposited on a platform, the article 22 is oriented in anupright disposition with its finish 14 disposed in a topmost locationready for operational engagement with a heating device in each of heattreatment stations 62, 63, the mandrel 28 at expansion station 26, andthe sizing device 100 at crystallizing station 63.

The shape, size, construction and arrangement of the mechanisms used tosupport and align the articles on the conveyor 67 can assume a varietyof suitable designs. In the embodiment shown in FIGS. 5-8, the bottles22 are automatically deposited into a recess 202 (see FIG. 6) formed byand between retaining mechanisms 206 that extend from the top of eachplatform 60. In the embodiment shown, the retaining mechanisms areformed as posts or fingers that project upwardly from the top surface200 of the platform 60. The recess 202 has a shape, size andconfiguration that is adjustable to be complementary in shape, geometryor configuration with the shape, size, geometry and configuration of theexterior side walls 22 a of a container such that a container 22 can bereadily deposited into and received within a recess 202.

In the embodiment shown in FIGS. 6-7, the support platform 60 has theform of a cylindrically shaped disc with a top support plate 230 havinga top surface 200 on which the bottom surface 25 (see FIGS. 3 and 4) ofthe article/container 22/40 is positioned. The top plate or disc 230 hasa radius R (see FIG. 7) from a central vertical axis 220 and the plateis provided with four radial slots 236 through which an axial mountingbolt 238 passes. The bolt 238 extends throughout the length of a hollowcylindrical bore in finger 206, enabling the four fingers 206 to beadjustably positioned or slid (see arrow 239) to any desired positionalong the length of the slot 236. When a finger has been slid to adesired position, the finger can be fixed at the desired position by thelower end of bolt 238 engaging with nut 232. Such adjustable positioningof the fingers enables the size/shape of a recess 202 to be selectivelymodified to accommodate the receipt of container bodies ofdifferent/varying sizes and shapes.

In the embodiment shown in FIGS. 6-7, a set-up fixture 37 shown inphantom can be used for setting the desired radial positioning of thefour fingers 206 in slots 236. The diameter of fixture 37 matches theouter diameter of the container body to be held in recess 202, and thusthe fingers are slid radially inwardly to engage fixture 37 and are thenlocked into position by tightening the bolt 238 into rectangular nut232. The set-up fixture 37 is then removed and the support platform isready to receive the container body.

FIG. 6 also shows a movable belt 222 mounted on a rotating pulley 224which engages an upper portion of each platform 60 to provide relativerotation of the container finish with respect to the mandrel 28 (andsizing device 100). Thus, when platforms 60 enter the expansion station26 (and crystallization station 63) the platforms are pushedtransversely with respect to conveyer 67 on path 6 by, for example, afixed rail (not shown) in order to engage the movable belt 222. Theplatforms (and the containers resting on the platforms) can be rotatedduring insertion/removal of the mandrel 28 and/or insertion/removal ofthe sizing device 100. It may also be desirable to rotate theplatforms/containers for uniform heating at stations 62 and 63.

In the embodiment shown, the article 22 is generally cylindrical orcircular in cross-section and the recess 202 is configured to acceptsuch a shape. Apart from cylindrical shapes, recess 202 and platform 60can be configured to receive and accommodate an article or container ofany given shape, size, geometry or configuration including withoutlimitation articles that are triangular, oval, square, rectangular,hexagonal or the like having rounded, curvilinear or sharply anglededges, indents, recesses, relief imprints and the like.

As previously discussed, the originally molded narrow-neck finish 14 ispreferably heated at station 62 (see FIG. 1) in a radiant ovenenvironment in which heat is directed at least at the material of thefinish 14 itself in order to soften the polymer material of which thefinish 14 is comprised. The finish temperature must be high enough sothat the material can be readily expanded upon insertion 29 of themandrel 28. For polyethylene terephthalate (PET) this means heatingabove the glass transition temperature. The T_(g) of PET typicallyranges from 172° F. (for a lower molecular weight PET) to 180° F. (for ahigher molecular weight PET). It is desirable to heat the surface of thefinish well above T_(g), e.g., from 220-260° F. The mandrel itself isheated between about 160°-195° F. in order to maintain an elevatedfinish temperature (i.e., prevent an unacceptable drop in the finishtemperature due to contact with a cold mandrel). Upon the insertionmovement (see downward arrow 29 in FIG. 5), the outer surface of thelower mandrel body 50 makes contact with the inner diametric surface 52of the neck 14 to cause the softened material of the narrow neck finish14 to gradually expand to the diameter of the intermediate mandrelportion 34 as shown in FIG. 11B. The mandrel has a central bore 82through which air may be directed into the article 22, 40 to support therelatively thin sidewall 24, e.g., during insertion of the mandreland/or cooling of the expanded finish.

After expansion, the widened neck 36 is preferably cooled by continuedinsertion of the mandrel (see arrow 29 a in FIG. 11C), thus positioningthe widened neck 36 over portion 35 of the cooled upper body 37 of themandrel 28. The cooled upper body portion 35 is cylindrical and has thesame diameter as the intermediate portion 34 of heated lower body 51.Upper and lower bodies 37, 51 respectively are mounted such that theyare thermally isolated from each other. In the embodiment shown in FIGS.10-11, a thermal insulator 66 is sandwiched between bodies 37 and 51.The insulator 66 comprises a disc of a non-heat conducting material,such as a ceramic, the disc having the same diameter as portions 34 and35. The disc 66 is mounted such that its top and bottom ends firmlyengage portions 34 and 35 respectively, whereby a seamless continuouscylindrical surface of a single diameter is formed between the threeportions 34, 66, 35 enabling the mandrel 28 to be fully inserted 29 a tothe position shown in FIG. 11C, in which position the undersurface 69(see FIG. 5) of widened collar 68 (on body 37) engages the top surfaceof the widened neck 36. The upper mandrel body 37 is cooled for exampleby injection of cold water CW, and/or by other means. The cooled upperbody portion 35 contacts the inner diametric surface 52 of the finish 36and thus acts as a heat sink, drawing heat out of the finish 36 byconduction contact. In the case described above where PET is the primaryneck material, the upper portion 37 is typically cooled to a temperaturebetween about 85°-115° F., before removal of the mandrel.

In the embodiment shown, the cooling fluid (CW) is injected intochannels 84 in the upper mandrel body 37. In contrast, a heating fluid(HW) is injected into and through insulated channels 86 in the upperbody 37, in order to reach the uninsulated channels 87 in the lowermandrel body 51 (and heat the body 51).

As best shown in FIGS. 10-11, the upper mandrel body 37 preferablyincludes a circumferential cooling collar 70 having channels 72 forinjection of a cooling fluid (such as cold air A) to cool the exteriorsurface 54 of the widened neck 36. The collar 70 is mounted to themandrel body 37 such that a chamber or annular slot 74 is formed betweena radially inwardly facing surface 76 of the collar 70, and a radiallyoutwardly facing surface of the upper mandrel portion 35, forming a“halo” of cooling air in the chamber 74 around the expanded finish. Asshown in FIG. 11C, the widened finish 36 is disposed within the chamber74 upon full insertion 29 a of the mandrel 28. The cooling air (A) ispreferably of a temperature that is significantly lower than thetemperature of the finish 36, e.g., cooling air (A) is less than about150° F., preferably less than about 100° F. and most preferably lessthan about 75° F. Standard room temperature (about 72° F.) compressedair can be used. The mandrel 28 may be left in the position shown inFIG. 11C for a time that is sufficient to cause the material of thefinish 36 to cool to a predetermined temperature and/or to allow thepolymer material of the finish to crystallize or partially crystallizeto a predetermined extent. Next, the mandrel 28 is removed 42 from thefinish 36 as shown in FIGS. 5 and 11D, typically via simultaneouslyrotating 31 the mandrel 28 together with the vertical removal movement(see arrow 42).

As shown in FIG. 10, the outer surfaces of the upper and lower bodies37, 51 that come into contact with the inner diametric surface 52 of thefinish are preferably coated with a layer 80 of low friction, non-stickmaterial to enable the mandrel 28 to be more readily inserted andremoved during the insertion and removal operations 29, 29 a and 42.Suitable examples of such low friction materials are polyfluorocarbonpolymer materials, e.g. a Teflon or Teflon-like material such aspoly(tetrafluoroethylene) (PTFE) orpoly(tetrafluoroethylene-co-hexafluoropropylene) (FEP).

Expansion of the container finish can be carried out in a single step asdescribed. Alternatively, the finish expansion can be carried out insequential stages before and after blow molding. For example, an initial28 mm finish may be expanded to 43 mm prior to blow molding thecontainer body, where the blow mold accepts a 43 mm neck diameterpreform. After blow molding, the finish could then be further expandedto 63 mm. As another modification, the finish could be slightlyover-expanded, and then allowed to shrink and relax. For example, thefinish could be expanded from 43 mm to 63.5 mm, and then allowed toshrink, perhaps onto a plug, to 63 mm. This would have the advantage ofallowing stress relief after expansion. Shrinkage could be induced byexposure to heat, such as during a crystallization operation.

By way of example, a finish 14 having an initial diameter of 28 mm canbe expanded in a first oven treatment 62 and mandrel insertion 29sequence to a finish 36 having a 43 mm diameter, or a diametricexpansion of about 53.6%. In another example, a 43 mm diameter finish 14can be expanded to a finish 36 having a 63 mm diameter, or an expansionof about 46.5%. In another example, a 28 mm diameter finish can beexpanded to a 63 mm finish diameter, with an expansion of about 125%. Inyet another example, a 63 mm finish diameter can be expanded to 83 mm,or an expansion of about 32%. The preform threads 16 and finish 14 willbe larger and thicker than those of the final finish 36 and are sized toarrive at the proper dimensions after stretching.

As shown in FIGS. 8-9, the sizing device 100 may comprise a hollow cupor cup-like body 124 of a highly thermally conductive material such as ametal, e.g., aluminum, iron, steel, copper and like metal materialsand/or alloys of one or more of such metals. The cup 100 has acircumferential outside surface 104 that is complementary to the size,shape and geometry of the inside surface 52 of the enlarged finish 36such that when the finish 36 is subjected to the second heat treatment63, the outside surface 104 of the cup 100 prevents the enlarged finish36 from shrinking in size to any size less than the size, circumference,diameter or the like of the surface 104 of the cup 100. By complementaryit is meant that the surface 104 is substantially the same size as thesize of the inside surface 52, such that the surface 104 preferablycomes into intimate engagement contact with surface 52 immediately uponinsertion 102 and/or upon shrinkage of the finish 36 a during the courseof the heat treatment process 63.

As shown in FIGS. 8-9, the cup 100 also has a beveled or conicallyshaped leading/bottom portion 112 having an outer circumferentialsize/diameter that is less than the inner circumferential size/diameterof the inside surface 52 of the expanded finish 36, such that the bottomcup portion 112 acts as a guide for insertion of the larger diameterupper surface portion 104 of the cup 100. The metal or other material ofthe cup body 124 is selected to function as a heat conductive sink, i.e.a body of material that is capable of acting as a repository of heattransmitted by conduction from the heated finish 36 to the cup body 124before, during and/or after the heat treatment step 63. Thus the cupbody 124 comprises a mechanism for cooling the heated finish 36. In apreferred embodiment, where the finish is PET, the finish exits thecrystallizing station 63 at a temperature of about 350° F. It should becooled to around 200° F.±20°, before removing the cup. This may beaccomplished by directing a stream of cold air into the top of the cupto cool the cup directly, and the finish indirectly (by contact with thecup). The cold air stream may also be directed onto the finish itself,to cool the finish directly. The cup 100 is preferably provided with anoutermost coating 120 of low friction, highly non-stick material (suchas previously described) to enable the cup 100 to be more readilyinserted and removed during the insertion and removal operations 102,108. Most preferably the bottle 40 is rotated (see arrow 106) around itsaxis during the insertion step 102 (by rotating platform 230) and thebottle is similarly rotated (see arrow 110) during the removal step 108.The bottom of the cup may have a central vent bore 122 to allow escapeof the volume of air displaced during insertion of the cup into thebottle, and thus prevent the cup from popping out of the bottle.

As shown on the left hand side of FIG. 8, the cup 100 is removed 108from the neck 36 after the oven treatment step 63 is complete. Thetiming of the removal step 108 (subsequent to completion of the heattreatment step 63) is selected to allow the heated neck 36 to cool to atemperature at which the neck will no longer shrink or otherwise deformor deviate in size to any significant degree, i.e. less than about 2%subsequent to completion of the crystallization step 63.

The stretching of the finish 14 and threads 16 may achieve anadvantageous molecular orienting in the expanded finish 36 and threads.The initial stretching may also strengthen the neck area of the finalcontainer 40. The second heat treatment step 63 may wholly or partiallycrystallize the material of the finish 36. Crystallization serves tochange the orientation of the polymer material from an amorphous stateto an ordered state that resists and/or prevents relaxation andshrinkage, particularly when the container is to be employed inhot-fill, refill, pasteurization or other high temperature applications.Such crystallization of the finish 36 can be partial, i.e. limited tothe exterior surface or to a relatively small depth from the surface ofthe finish including the threads, or may extend more deeply through aportion of the thickness of the finish or may extend entirely throughthe entire thickness of the container finish 36.

In an alternative embodiment, a crystallization step can be carried outsimultaneously with insertion of the mandrel 28 to stretch/widen thefinish 14. For example, the mandrel 28 can be inserted 29 during thecourse of a first heat treatment step (such as 62 as described above),and a time and temperature employed (when the mandrel is in the FIG. 11Bor C position), along with timing of the removal of the cooled uppermandrel portion 35 to allow the finish 36 to both stretch upon insertion29 of the mandrel 28 and to allow the stretched finish 36 to crystallizeor partially crystallize to a selected degree prior to removal 42 of themandrel 28. As described in the preferred embodiment regarding insertionof the cup 100, insertion of the mandrel 28 during step 62 may preventthe widened neck 36 from shrinking in size as well as to cool thematerial of the neck 36. The subsequent crystallization or partialcrystallization in the neck material 36 then stabilizes the widened neck36 against shrinkage such that the mandrel 28 can be removed 42 withoutrisk of significant further shrinkage (thus mitigating the need for theseparate steps of insertion and removal of the sizing cup).

These and other modifications would be readily apparent to the skilledperson as included within the scope of the described invention.

1. Apparatus for treating a series of molded plastic articles, eacharticle having a relatively wide and thin-walled blow-molded bodyportion and a relatively narrow and thick-walled unexpanded neck finishportion, the apparatus comprising: a series of platforms carried by aconveying apparatus that transports the platforms along a predeterminedpath of travel through a finish widening station; each platform having atop surface and a mating mechanism for engaging the body portion of onearticle, the top surface engaging a bottom surface and the matingmechanism engaging a sidewall surface of the body portion of the onearticle; the finish widening station comprising a mandrel insertablewithin and removable from an open top aperture of the finish portion towiden the finish portion, wherein the mandrel has a lower tapered bodyportion insertable into the open top aperture of the finish portion forwidening the neck finish portion from a first neck size to an expandedsecond neck size and the mandrel further includes a cooled upper bodyportion of the second expanded neck size for cooling the expanded neckfinish portion; and the mating mechanism adjustably receiving andengaging against the sidewall portion to hold the one article in asteady position relative to the platform during insertion and removal ofthe mandrel from the aperture.
 2. The apparatus of claim 1, wherein themating mechanism comprises two or more fingers extending upwardly fromthe top surface of the platform and forming a recess between the fingersthat engages the sidewall portion.
 3. The apparatus of claim 2, whereinthe fingers are adjustably mounted on the platform to move along a pathtoward and away from a more central point of the platform, the fingersbeing fixable at selected positions along the path of movement.
 4. Theapparatus of claim 1, wherein one or more of the platform and mandrelare rotatable for rotating the finish portion with respect to themandrel.
 5. The apparatus of claim 1, wherein the lower body portion ofthe mandrel is heated by a flow of fluid through channels in the lowerbody portion.
 6. The apparatus of claim 5, wherein the upper bodyportion is cooled by a flow of fluid through channels in the upper bodyportion.
 7. The apparatus of claim 6, wherein the mandrel includes anexternal cooling mechanism for directing a cooling fluid into contactwith an exterior surface of the widened finish portion.
 8. The apparatusof claim 7, wherein the external cooling mechanism provides a ring ofcooling fluid to and around the exterior surface of the widened finishportion.
 9. The apparatus of claim 8, wherein the external coolingmechanism comprises a collar mounted on the upper body portion of themandrel.
 10. The apparatus of claim 8, wherein the cooling fluidprovided by the external cooling mechanism is air.
 11. The apparatus ofclaim 6, wherein the fluid in the channels of the upper body portion iscold water.
 12. The apparatus of claim 5, wherein the fluid in thechannels of the lower body portion is hot water.
 13. The apparatus ofclaim 1, wherein the predetermined path of travel includes a finishcrystallizing station comprising a heating device that heats the widenedfinish portion for a time and temperature selected to crystallize atleast a portion of the widened finish portion.
 14. The apparatus ofclaim 13, wherein the finish crystallizing station includes a sizingdevice insertable within and removable from the widened finish portion.15. The apparatus of claim 1, wherein the treated molded plasticarticles are food or beverage containers.
 16. The apparatus of claim 1,wherein the upper body portion is cooled by a flow of fluid throughchannels in the upper body portion.
 17. The apparatus of claim 1,wherein the mandrel includes an external cooling mechanism for directinga cooling fluid into contact with an exterior surface of the widenedfinish portion.
 18. The apparatus of claim 1, wherein an outer surfaceof the mandrel comprises a low friction material.
 19. The apparatus ofclaim 1, wherein the upper body portion of the mandrel is cylindrical.20. The apparatus of claim 1, wherein the mandrel is rotatable.